Conversion of liquid carbonaceous materials into hydrocarbons of low boiling point



M. PIER El AL CONVERSION oF LIQUID cARBoNACEoUs MATERIALS March 5., 1935.

INT0 HYDROCARBONS oF Low BOILING POINT Filed Aug. 28, 1930 Patented Mar. 5, 1935 UNITED STATES 1,999,226 l coNvEnsroN or LrQUm cAasoNAcEoUs MATERIAL S INTO HYDROQARBONS F l LOW BOILING POINT Mathias Pier, Heidelberg, and Heinz Mannheim, Ge

rmany, assignors to I. G. Parbeniml'ustrie Aktiengesellschaft, Frankfort-onthe-Main, Germany Application August 28,

In Germany 4 ciaims.

The present invention relates to improvements .in the conversion into hydrocarbons of low boiling point, for example by cracking or by destruc tive hydrogenation, of liquid carbonaceous mate- 5 rials, in particular of those containing solid substances, nely dispersed and asphaltic constituents dissolved in the said materials.-

In the destructive hydrogenation or cracking of liquidcarbonaceous materials such as mineral oils, distillation products of mineral oils boiling above 300 C. and which contain asphalt, or of all varieties of coal, for example tars, or their conversion products, there was hitherto the ob- Jection that, .after the process was in continuous operation for some time, particularly when the conditions were so adjusted that a complete destructive hydrogenation of the initial materials and saturation of the resultant products was not obtained, solid materials initially dispersed in the said initial materials or formed at the high temperatures employed from asphaltic materials dissolved therein, were precipitated .and deposited on the catalysts, thereby slowly but surely decreasing the active surface of the catalysts until a point was reached where the properv eiciency of the process could only be attained by interrupting the process and removing the layer of precipitated, carbonaceous material from the surface of the catalyst. t

We have now found that this objection is overcome and that the conversion by heat-treatment of liquid carbonaceous materials into hydrocarbons of lower boiling point is carried out with great advantage by first adding to the initial materials solid or liquid hydrocarbons rich in hydrogen, whereby the asphaltic materials dissolvedl in the said materials are caused to precipitate out and to carry down the solid particles, such as carbon or dust, dispersed in the initial materials, and then subjecting the products separated from the precipitated substances to conversion by heat-treatment, such as cracking or destructive hydrogenation. When pretreating the initial inaterials, in the manner. described, the deposition of solid substances on the catalysts is reduced to a' minimum and the latter maybe employed continuously for a long period of time.

1930, Serial No. 478.553 v October 3, 1929 tion tar residues, also'waxes, such as paraln wax, stearin and the. like.

The amount of the hydrocarbons rich in hydrogen to be added depends on the character, especially on the asphalt content, of the materials to be worked up and is preferably selected so that a more or less strong iiocculation of the asphaltic materialtakes place, whereby the solid impurities nely dispersed in the tar or the like are enclosed and carried down. The conglomeration of the solid particles thus effected resultsin the tar or the like being rendered suitable for filtering or centrifuging in a very short time. A product entirely free ,from solid constituents is thus obtained. In case the subsequent conversion by heat-treatment is Aeifected with the aid lof catalysts which are nely divided 'in the initial materials, mainly the solid particles dispersed in said initial materials are injurious andv only such amounts of asphaltic bodies are to be precip. itated as are sumcient for carrying down the said' solid particles present in a dispersed state.

For this purpose the precipitating hydrocarbons' rich in hydrogen are as a rule added in an amount of up to 20 per cent by weight, reckoned on the initial materials. I! it is desired to carry out the heat-treatment with catalysts permanently arranged in the reaction vessel, for example on the stirring devices, it is advisable to precipitate substantially'the whole amount of asphaltic materials contained in the materials to be treated, whereby lsimultaneously any solid particles present in the initial material are precipitated. This is usually attained by an addition of up to 30 per centv and even more of hydrocarbons rich in hydrogen.

The asphaltic in the appended claims is a high molecular hydrogen-poor hydrocarbon material which contains small amounts of oxygenor oxygen and sulphur, which asphaltic material is precipitated from or dispersed in the starting materials by means of benzine or hydrogen-rich'hydrocarbons of highmolecular weight and which is inRpart precipitated from its solution'in ether by the ad'- dition of alcohol (see Holde Kohlenwasserstoffoele und Fette 1933, p.V 164). The molecular above 600 and can be asmuch as 2000 or more. It is difllcult to assign an` exact value to the hydrogen content of the asphaltic material, since this varies with the particular asphaltic material under consideration. Asphaltic material from. tar oils contains only about 6% of hydrogen,

weight of such asphaltic material is, as a rule.,

lmaterial referred to herein and 4 while mineral oil asphaltic material may contain as much as 12% of hydrogen or more.

The separation of precipitated constituents may be eiected in the usual manner, for example by ltering or by centrifuging. The precipitation itself. may be carried out at atmospheric pressures and preferably while warming, for example to temperatures ranging from 50 to 150 C., but also higher or lower temperatures may be employed. Good results are also obtained by warming the materials to be purified with the said hydrocarbons rich in hydrogen under elevated pressures, preferably at a pressure of from about 5 to 10 atmospheres.

According to the present invention the materia1s thus purified are then subjected to a conversion into hydrocarbons of lower boiling point either together with the added hydrocarbons rich in hydrogen or after separation fromthe latter, which separation may be eiected for example by distillation. In case the. subsequent conversion is eiected by' a. destructive hydrogenation, the materials purified are subjected in the liquid or vaporous phase to the action of hydrogen at temperatures above 300 C., preferably between 350 and 600 C. and at elevated pressures of at least 20 atmospheres, preferably above 50 atmospheres. As catalysts come into question those speciiied in the Australian` Letters Patent No. 1,217 of '1926. Catalysts which are of particular advantage are Vthe sulphides of heavy metals in particular those of group 6 of the periodic system such as molybdenum, tungsten, uranium or chromium, or of vanadium, or the metals'or compounds, such as oxides, of silver, zinc, copper, lithium, aluminium, cadmium, lead, bismuth, magnesium, silicon, titanium. 'I'hese catalysts may be employedY as such or applied to carriers such as bauxite, asbestos, quartz, active silica.

The pretreatment of the initial materials `with hydrocarbons rich in hydrogen as effected according to the presentinvention is especially advantageous in destructive hydrogenation processes carried out at relatively high temperatures since in this case the. asphatic bodies contained in the materials to be treated have a great tendency to form coky or resinous masses smearing the catalysts employed and thus are injurious to a particularl-y great extent.

In case the liquid carbonaceous materials puried according to the present invention are subjected to cracking, the conditions ordinarily used for cracking may be employed. The cracking is effected at temperatures of at least 300 C., preferably between 380 to 550 C. and in the presence or absence `of hydrogen, and with or without the aid of elevated pressure.

An apparatus suitable for carrying out our in' vention is illustrated diagrammatically in the accompanying drawing which bears legends which are suiiiciently descriptive of the mode of operation to render further description thereof unnecessary. v

'I'he following examples will further illustrate the nature o1' this invention, but the invention is not restrictedtolthese examples.

Example 1 A mineral coal crude tar containing 4 per cent of solid constituents which consist of light ashes' and particles of cokeis stirred at100 C. with about 40 per cent of a low temperature carbonization tar residue having a hydrogen content of'between 14 and 15 per cent by weight and the mixture is then for 15 minutes at 100 C.;

A tar which is practically free from solid constituents and asphaltic material on the one hand and a residue containing from about 40 to 50 per cent of solid constituents von the other hand are obtained.

If the said mineral coal crude tar is mixed with its own weight of a low temperature carbonization tar residue rich in hydrogen and then heated for about 30 minutes in a closed vessel to a temperature of about 200 C., a particularly pure product is obtained after cooling down to about 100 C. and centrifuging. `In this case, the separation of the solid particles from the liquid may also be effected by simply allowing the said solid particles to settle down.

The product puried as hereinbefore described is then passed together with hydrogen at 450 C. and at a pressure of 200 atmospheres over a catalyst consisting of molybdic acid, chromic acid and manganese carbonate and which is permanently arranged in the reaction vessel. 'I'he 'products issuing from the reaction Vvessel repreconstituents areobtained. This -puriiled tar is` then freed from tetrahydronaphthalene by distillation, whereupon it is passed together with hydrogen at 460 C. and at a pressure of 200 atmospheres over a catalyst consisting of tungstic acid and magnesium oxide. A valuable product mainly consisting of benzine and middle oil y is thus obtained.

Example 3 A mineral coal high temperature tar containing 5 per cent of solid constituents is stirred at C. with 20 per cent of gas oil for about 15 minutes and the mixture is centrifuged at the same temperature. I'he centrifuged tar no longer contains solid constituents while the residue contains 50 per cent of solid constituents. The thus pretreated tar containing about 10 per cent of asphaltic material is then treated together with hydrogen in the liquid phase at 400 C. and at a pressure of 200 atmospheres in the presence of a catalyst consisting of equimolecular proportions of molybdenum oxide, zinc oxide and mag.

nesium oxide and which is introduced into the reaction vessel in a nely ground state together withvthe materials to be converted. A product substantially consisting of middle oil is thus obtained.

What we claim iszv 1. In the production of hydrocarbons of lower boiling point from an impure liquid carbonaceous material containing asphaltic material by `subjecting said initial material to a conversion at g temperature of at least 300 C., the preliminary fsteps of precipitating asphaltic material dissolved in said initial material by adding to said initial material a substance essentially comprising par- 2. In the production of hydrocarbons of lower boiling point from an impure liquid carbonaceous material containing asphaltic material and having solid particles dispersed therein by subject- 5 ing said initial material to a conversion at a temperature oi.' at least 300 C.l in the presence of a catalyst, the preliminary steps of'removing the solid particles from said initial material by precipitating at least parto! the asphaltic mam terial dissolved in said initial material by adding to said initial material a substance essentially comprising paramn wax and removing the precipitated constituents from said initial material. 3. The process according to the preceding claim in which the conversion referred to is a destructive hydrogenation.

4. The process according to claim 1 in which the precipitation step is carried out at a temperature between 50 and^150 C. and under a pressure of from 5 to 10 atmospheres.

MATHIAS PIER. HEINZ LEMME. 

